In other words, 821 nails is 0.0067396 times the height of Aconcagua, and the height of Aconcagua is 148.38 times that amount.

(a.k.a. Cerro Aconcagua) (Mendoza, Argentina)Aconcagua measures 121,820 nails height at its peak. Although there is no definitive evidence that members of the indigenous Inca civilization ever reached the peak the mountain, numerous archeological sites have been found on the slopes of the mountain, including a naturally-embalmed Incan mummy was discovered on a 90,989 nails high ridge.

In other words, 821 nails is 0.005118 times the height of a Mauna Loa, and the height of a Mauna Loa is 195.4 times that amount.

(Hawaii) (Hawaiian island volcano) (total height from seafloor)Mauna Loa, one of the five volcanoes which forms the island of Hawaii and the tallest mountain in total height in the world, rises to 161,000 nails above the seafloor. The peak of Loa is home to the approximately 6,000 sq. m (0.6 ha) Lake Waiau, one of the highest altitude lakes in the United States outside of Colorado.

It's about one-two-hundred-fiftieth as tall as The Challenger Deep (Marianas Trench).

In other words, 821 nails is 0.0043038 times the height of The Challenger Deep (Marianas Trench), and the height of The Challenger Deep (Marianas Trench) is 232.35 times that amount.

(near Marianas Islands, a.k.a. Ladrones Islands, northwestern Pacific Ocean) (depth below sea level)The Challenger Deep, at the southern end of the Marianas Trench, reaches a depth of 190,760 nails below sea level. There has been only one manned expedition to the bottom of Challenger Deep — a 1960 voyage that took 4 hours and 48 minutes to reach the bottom.

(Ishtar Terra, Venus)Maxwell Montes rises to a total height of 190,000 nails. Since Venus does not seem to have the kind of tectonic activity which gives rise to mountains on Earth, the origin of the Venusian mountain remains the subject of some dispute.

In other words, 821 nails is 0.0017 times the height of Olympus Mons, and the height of Olympus Mons is 590 times that amount.

(a.k.a. Mount Olympus) (Mars)The tallest mountain in the solar system, Olympus Mons rises to approximately 470,000 nails. The mountain has been known to astronomers since the nineteenth century because it is tall enough to rise above Mars' frequent dust storms.

The most common golf tee size and the length preferred for iron and most wood clubs is 0.94 nails tall. The tee did not come into common use until it was promoted by professional golfers Walter Hagen and Joe Kirkwood, as part of a marketing effort by the patent-holder of the well-known, "Reddy Tee."